Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 2, pp. 295−300.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
M.V. Pyatygina, G.R. Mingaleeva, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 2, pp. 301−306.
AND INDUSTRIAL ORGANIC CHEMISTRY
Simulation of Degradation of Coal Organic Matter
M. V. Pyatygina and G. R. Mingaleeva
Research Center for Power Engineering Problems, Kazan Scientiﬁ c Center,
Russian Academy of Sciences, Kazan, Tatarstan, Russia
Received March 6, 2008
Abstract—The existing procedures for calculating thermodynamic functions of individual compounds of coal
organic matter were analyzed, and possible reactions of its degradation were simulated. The possibility of the
occurrence of pyrolysis reactions in the forward direction with the formation of methane, propane, and other
saturated hydrocarbons as target products was examined by calculation of the Gibbs energies using an additive
procedure for determining the thermodynamic functions of structural fragments and data on the composition of
coal from Kuznetsk coal fields. The chemical and thermodynamic relationships between the starting compounds
and pyrolysis products were examined, and the temperature intervals of the reactions were determined.
The efﬁ ciency of coal utilization in the modern
power engineering is about 20%, and in the coming
years it is required to increase this parameter to 30–40%
. Therefore, it becomes necessary to use combined
procedures for thermochemical transformation of coal,
along with methods for increasing the efﬁ ciency of
direct combustion of coal in combustion chambers of
This complex problem can be solved only by widely
introducing procedures for thermochemical processing
of coal, with the formation of a wide range of products
that can be used in power engineering and industry.
Gasiﬁ cation and pyrolysis of coal, performed both sepa-
rately and in combination with each other, yield producer
gas with a caloriﬁ c value of 4000 to 20000 kJ kg
depending on the process conditions, and also coal tars
and cokes. Producer gas is of the greatest interest for use
in power engineering, as it can be used instead of natural
gas in combustion chambers of gas turbine units (GTUs)
or of steam boilers. However, wide use of coal-chemical
processes in power engineering is hindered by the lack
of reliable engineering procedures for calculating the
pyrolysis and gasiﬁ cation processes.
In this study, the possibility of the occurrence of
chemical reactions leading to formation of pyrolysis
gas, coal tar, and coke as ﬁ nal products from the initial
substances of the organic matter of coal (OMC) is
evaluated by simulation of the OMC degradation process.
Using the equations of known chemical reactions, it is
possible to estimate the power expenditure for performing
the process, and also the process parameters: temperature,
pressure, and time. It will thus become possible to develop
efﬁ cient ﬂ owsheets for preparing high-energy gas by
thermochemical processing of coal.
Pyrolysis is one of procedures for thermochemical
processing of coal. It occurs in the temperature range
120–1000°C. Pyrolysis occurs in the course of industrial
processes of coal coking and semicoking. The mechanisms
of these processes and the actually functioning systems
are described in detail in . However, these processes
were mainly demanded by metallurgy and chemical
technology, and therefore the major goal was improving
the quality of coke and semicoke as target products.
Today a somewhat different approach is required, aimed
at integrated utilization of the solid fuel and generation
of thermal and electrical energy.
When coals are gradually heated under anaerobic
conditions, ﬁ rst water vapor is released. At 250°C, CO
S can also be detected, and at approximately
300°C condensing liquid products start to evolve and a
noticeable amount of water is formed, i.e., the organic
matter of coal starts to degrade. The majority of liquid
products appear in the range 300–400°C, and this process
ends at 550°C with the formation of primary tar [2, 3].